CODIF Status Lynn Kistler, Chris Mouikis Space Science Center UNH July 6-8, 2005 Paris, France

Outline H+ Efficiencies H+ Efficiencies O+ Efficiencies O+ Efficiencies Moments comparisons Moments comparisons Comparisons with FAST/TEAMS Comparisons with FAST/TEAMS

H+ Efficiencies Temporal Changes. Temporal Changes. The temporal changes in the absolute efficiency are determined using the “Monitor Rates” The temporal changes in the absolute efficiency are determined using the “Monitor Rates” Start rate (SF) Start rate (SF) Stop rate (SR) Stop rate (SR) Coincidence Rate (SFR) Coincidence Rate (SFR) Single event rate (SEV) Single event rate (SEV) These allow us to monitor the start efficiency (SFR/SR), stop efficiency (SFR/SF) and the fraction of coincidences that also have a single position signal (SEV/SFR). These allow us to monitor the start efficiency (SFR/SR), stop efficiency (SFR/SF) and the fraction of coincidences that also have a single position signal (SEV/SFR). The product of these values gives the total efficiency. The product of these values gives the total efficiency. The stop rate (SR) is not completely reliable, which gives some uncertainty in the final answer. The stop rate (SR) is not completely reliable, which gives some uncertainty in the final answer.

Temporal Changes Following the last meeting, the MCP voltages were increased as follows: Following the last meeting, the MCP voltages were increased as follows: July 12 and 24, 2004: All SC increased two steps. (values SC1/150, SC3/150, SC4/150) July 12 and 24, 2004: All SC increased two steps. (values SC1/150, SC3/150, SC4/150) Result - OK, on all spacecraft Result - OK, on all spacecraft Sept 25, 2004: All SC increased two steps (values SC1/152, SC3/152, SC4/152) Sept 25, 2004: All SC increased two steps (values SC1/152, SC3/152, SC4/152) Result - some discharges in SC3 - reduced to 150 on 10/12/04 Result - some discharges in SC3 - reduced to 150 on 10/12/04

SC1/FM8 Efficiencies start stop Single event 2000/9/01 1-year Whole mission

SC4/FM7 Efficiencies start stop Single event 1-yearWhole mission

SC3/FM6 Efficiencies start stop Single event 1-yearWhole mission

Total Efficiency for all Spacecraft

Separate Anode Efficiencies In order to accurately measure the velocities and pitch angle distributions, the efficiencies of individual anodes need to be known. In order to accurately measure the velocities and pitch angle distributions, the efficiencies of individual anodes need to be known. This is determined by using time periods when the ion distribution is expected to by gyrotropic, and normalizing the anodes so that they are the same at the same pitch angle. This is determined by using time periods when the ion distribution is expected to by gyrotropic, and normalizing the anodes so that they are the same at the same pitch angle.

SC1 Anode Efficiencies One month before anomaly

SC4 Anode Efficiencies Dec, 2004

SC3 Anode Efficiencies Feb, 2003 Anodes 5-8 are so far below the other anodes that it is almost impossible to calibrate them. In addition, including them adds spikes to the data, because one count converts to such a high flux. Therefore, we decided to no longer include anodes 5-8 when calculating fluxes. Any counts are zeroed, using the calibration files.

SC3 pitch angle distribution Note that SC3 still produces very good data using anodes 1-4. In most cases it still measures a complete pitch angle distribution (depends on field configuration). The main loss is the measurement of Vz.

Separate Anode Efficiencies Conclusions SC4 and SC1 (up to the anomaly) SC4 and SC1 (up to the anomaly) Difference between anodes can easily be accounted for in the calibration files. Difference between anodes can easily be accounted for in the calibration files. For SC3 For SC3 the difference between anodes 1-4 and 5-8 is so big that we can no longer accurately determine the anode 5-8 efficiency. the difference between anodes 1-4 and 5-8 is so big that we can no longer accurately determine the anode 5-8 efficiency. Because the efficiency is so low, single counts observed on these anodes are calculated as a very high flux and introduce spikes on plots vs time Because the efficiency is so low, single counts observed on these anodes are calculated as a very high flux and introduce spikes on plots vs time Anodes 1-4 are still quite good, and in most areas we still get complete pitch angle distributions using half the instrument. Anodes 1-4 are still quite good, and in most areas we still get complete pitch angle distributions using half the instrument. Therefore, starting on Feb 24, 2003, we no longer include anodes 5-8. These anodes are zeroed out in the efficiency files. Therefore, starting on Feb 24, 2003, we no longer include anodes 5-8. These anodes are zeroed out in the efficiency files. Programs which calculated flux need to be changed so that the calculation assumes only anodes 1-4 are included. Programs which calculated flux need to be changed so that the calculation assumes only anodes 1-4 are included.

O+ Efficiencies Anode Efficiencies. Anode Efficiencies. Anode efficiencies can be determined in exactly the same way they are for H+: by using time periods when the distribution is gyrotropic and there is sufficient O+ flux. This works well, and the results are similar to O+ Anode efficiencies can be determined in exactly the same way they are for H+: by using time periods when the distribution is gyrotropic and there is sufficient O+ flux. This works well, and the results are similar to O+ Absolute Efficiencies. Absolute Efficiencies. To determine absolute efficiencies, we need time periods when the composition is almost pure O+. To do this we use the time periods when we see O+ beams in the polar cap. To determine absolute efficiencies, we need time periods when the composition is almost pure O+. To do this we use the time periods when we see O+ beams in the polar cap. Since the beams are normally observed in only one anode, we then use the anode efficiencies to normalize the measurement to the whole instrument. Since the beams are normally observed in only one anode, we then use the anode efficiencies to normalize the measurement to the whole instrument. The beam procedure is done using SC1. We then use comparisons between SC to get the absolute efficiencies for SC3 and SC4. The beam procedure is done using SC1. We then use comparisons between SC to get the absolute efficiencies for SC3 and SC4.

SC1 O+ Efficiency O+ efficiency using O+ beam data

SC3 and SC4 O+ Efficiency

Plasma Sheet CODIF H + SC1, SC3, SC4 The density shows a good agreement between all SC The velocity components from SC3 don’t agree because only one hemisphere is used

Plasma Sheet CODIF H + One hemisphere - Instrument coord. SC1, SC3, SC4 Here moments from the 3 SC in instrument coordinates, calculated using the one hemisphere (top) are plotted All moments show a good agreement confirming that the SC3 top hemisphere provides good data.

Plasma Sheet CODIF O + 1 – 40 keV – Instrument coord. SC1, SC3, SC4

Plasma Sheet CODIF H + One hemisphere – Instrument coord. SC1, SC3, SC4

Plasma Sheet CODIF O + 1 – 40 keV – Instrument coord. SC1, SC3, SC4

2003 CODIF – HIA Comparison SC1 - CODIF, SC1 - HIA Comparison between CODIF and HIA moments for SC1 The density calculated by HIA, inside the magnetosphere, is lower by a factor of ~2 compared to the CODIF density The velocity components show a good agreement

2004 CODIF – HIA Comparison SC1 - CODIF, SC1 - HIA

Efficiency Summary H+ and O+ HS efficiencies have been calculated through the end of The files are available. H+ and O+ HS efficiencies have been calculated through the end of The files are available. SC4 continues to operate very well SC4 continues to operate very well SC3 works well on one half. Using that half we can get reliable fluxes, densities, temperatures and pitch angle distributions. Vz cannot be measured. SC3 works well on one half. Using that half we can get reliable fluxes, densities, temperatures and pitch angle distributions. Vz cannot be measured. SC1 worked very well until the anomaly. We hope that we will get it operating again soon. SC1 worked very well until the anomaly. We hope that we will get it operating again soon.

Comparisons with FAST/TEAMS The FAST/TEAMS instrument is almost identical to CODIF The FAST/TEAMS instrument is almost identical to CODIF It has been operating for almost 9 years - since August, 1996 It has been operating for almost 9 years - since August, 1996 Comparisons with FAST/TEAMS will give us some idea what to expect in the extended mission. Comparisons with FAST/TEAMS will give us some idea what to expect in the extended mission.

FAST/TEAMS Efficiencies After a significant increase in MCP voltage after the first year, the MCP voltage was kept constant for more than 3 years. Thus after 4 years, the efficiency had declined to 1% of the original value. After a significant increase in MCP voltage after the first year, the MCP voltage was kept constant for more than 3 years. Thus after 4 years, the efficiency had declined to 1% of the original value. A series of increases in 2002 brought it up to a level where the instrument again took reasonable data. A series of increases in 2002 brought it up to a level where the instrument again took reasonable data. After 8.5 years it is operating at about 6- 10% of the original efficiency. After 8.5 years it is operating at about 6- 10% of the original efficiency. By occasionally increasing the voltage, the efficiency is being kept fairly constant By occasionally increasing the voltage, the efficiency is being kept fairly constant The FAST MCP voltage has increased 14% from 2.9 to 3.4 kV over the mission. CODIF has so far increased 7%. The FAST MCP voltage has increased 14% from 2.9 to 3.4 kV over the mission. CODIF has so far increased 7%.

Recent FAST Data (June 26, 2005) Teams Data All-Ion Data H+ He+ O+

Conclusions Despite reduced efficiencies, TEAMS continues to provide composition information after almost 9 years. Despite reduced efficiencies, TEAMS continues to provide composition information after almost 9 years. In addition, because of the coincidence requirements, it continues to give reliable fluxes in the radiation belts, where the all-ion instruments cannot function. In addition, because of the coincidence requirements, it continues to give reliable fluxes in the radiation belts, where the all-ion instruments cannot function. We expect that CODIF on CLUSTER will similarly continue to perform for the duration of the extended mission. We expect that CODIF on CLUSTER will similarly continue to perform for the duration of the extended mission.